Differential effects of body fatness and body fat distribution on risk factor for cardiovascular disease in women. Impact of weight loss

The skinny on obesity and plasma cell myeloma: a review of the literature

Despite tremendous advances in treatments for myeloma in the past decade, the disease remains incurable in the majority of patients. Here, we review recent data demonstrating an association between obesity and increased risk of myeloma development. This may be due to the pro-inflammatory cytokine profile caused by obesity. Currently, there are no screening or prevention strategies for myeloma, but we propose that obesity-associated inflammatory pathways, or obesity itself, may be amenable to intervention, thereby preventing the transition from pre-malignancy to myeloma. In addition, we suggest that the morbidity, mortality and the significant costs associated with myeloma treatment could be reduced by addressing modifiable risk factors, and that research efforts should explore this novel hypothesis.

Impact of religious Ramadan fasting on cardiovascular disease: a systematic review of the literature

BACKGROUND

Fasting during the month of Ramadan is a religious obligation that is practiced by millions of people around the world yet there is no clear scientific consensus on its effects on cardiovascular disease. This study was performed to inform physicians as well as patients of evidence based recommendations on this subject.

AIM

The study was undertaken to assess: (1) any alteration in the incidence of acute cardiac illness during Ramadan fasting; (2) whether fasting during the month of Ramadan alters the clinical status of patients with stable cardiac disease; and (3) the impact of Ramadan fasting on cardiovascular risk factors in normal subjects, in patients with stable cardiac disease, metabolic syndrome, dyslipidemia, type 2 diabetes and systemic hypertension.

STUDY DESIGN

Systematic review of the literature.

METHOD

A Medline search of the English literature published between January 1980 and September 2012.

RESULTS

The incidence of acute cardiac illness during Ramadan fasting was similar to non-fasting days, although the timing of symptom onset may be different, with significant increase in events during the period of 'breaking fast' when compared to non-fasting days. The majority of patients with stable cardiac illness can undergo Ramadan fasting without any clinical deterioration. Body mass index, lipid profile, and blood pressure showed significant improvement in normal healthy subjects, patients with stable cardiac illness, metabolic syndrome, dyslipidemia and hypertension during Ramadan fasting. The lipid profile of diabetic patients deteriorated significantly during Ramadan fasting.

CONCLUSIONS

Ramadan fasting is not associated with any change in incidence of acute cardiac illness and the majority of cardiac patients can fast without any difficulty. Improvement in lipid profile, especially 30% to 40% increment in high-density lipoprotein, as reported in some studies, appear promising. Diabetic patients should be carefully monitored during Ramadan fasting.

Regulation of FAT/CD36 mRNA gene expression by long chain fatty acids in the differentiated 3T3-L1 cells

Defects in fatty acid translocase (FAT/CD36) have been identified as a major factor in insulin resistance and defective fatty acid and glucose metabolism. Therefore, understanding of the regulation of FAT/CD36 expression and function is important for a potential therapeutic target for type II diabetes. We differentiated 3T3-L1 preadipocytes into matured adipocytes and examined the roles of insulin and long chain fatty acids on FAT/CD36 expression and function. Our results indicate that FAT/CD36 mRNA expression was not detected at preadipocyte but was significantly increased at matured adipocyte. In fully differentiated 3T3-L1 adipocytes, insulin significantly increased FAT/CD36 mRNA and protein expression in a dose dependent manner. The free fatty acid stearic acid reduced FAT/CD36 mRNA expression while the non-metabolizable free fatty acid alpha-bromopalmitate (2-BP) significantly increased FAT/CD36 mRNA and protein expression. Isoproterenol, in contrast, dose-dependently reduced FAT/CD36 mRNA expression and increased free fatty acid release. Mechanism analysis indicated that the effect of insulin and 2-BP on the FAT/CD36 mRNA gene expression may be mediated through activation of PPAR-gamma, suggesting that FAT/CD36 may have important implications in the pathophysiology of defective fatty acid metabolism.

Decrease in visceral fat following diet-induced weight loss in upper body compared to lower body obese premenopausal women

BACKGROUND

Obesity is associated with numerous metabolic disturbances, such as insulin resistance, diabetes mellitus type 2, dyslipidemia, and hypertension. An excess of fat within the abdomen, so-called visceral adiposity, confers a greater and independent health risk of metabolic and cardiovascular complications than does adipose tissue accumulation elsewhere. The present study aimed to investigate a possible differential effect of diet-induced weight loss in visceral fat mass and metabolic parameters in obese individuals with the upper body (UBO) and lower body (LBO) obese phenotype.

METHODS

The obese subjects were prescribed a liquid, very-low calorie diet to reduce 50% of their overweight (15% body weight loss). Specific body fat measurements (MRI, BIA), anthropometrics, and fasting metabolic parameters were obtained in control subjects and two groups of obese subjects (UBO and LBO) before and after weight loss.

RESULTS

Weight loss was accompanied by significant decreases in total, subcutaneous, and visceral fat in both UBO and LBO women. The largest reduction in visceral fat mass was found in the UBO women (absolute decrease 223+/-32 cm(2) vs 122+/-91 cm(2) in LBO women; P=0.01), while the amount of visceral fat was reduced to normal levels in LBO women (155+/-25 cm(2) after weight loss vs 143+/-17 cm(2) in controls; P=NS). Furthermore, weight loss significantly lowered fasting glucose, total cholesterol, and LDL cholesterol concentrations in UBO women.

CONCLUSION

The obese phenotype is preserved after body weight loss. UBO women have to lose a larger amount of overweight in order to bring the amount of fat in the visceral depot down to normal levels and to obtain normalization of their cardiovascular risk profile.

Prospective and controlled studies of the actions of insulin and catecholamine in fat cells of obese women following weight reduction

AIMS/HYPOTHESIS

Enlarged fat cells from obese subjects are characterised by insulin resistance and abnormal adrenergic regulation of lipolysis. The aim of the present study was to examine whether these aberrations return to normal following weight reduction.

MATERIALS AND METHODS

Obese women (n=25) were investigated before and 3+/-1 years (mean+/-SD) after steady-state weight reduction and compared with control women who were matched to the cases at re-examination in terms of age and BMI. Adipocyte volume, lipogenesis and lipolysis were determined in isolated subcutaneous fat cells following stimulation or inhibition at different steps of the lipolytic cascade.

RESULTS

Weight reduction decreased fat cell volume and basal and adrenergic-regulated lipolysis rates to values that were 20-40% lower than those in control women (p=0.0002-0.03), despite the fact that percentage body fat was almost identical in the two groups of women. Fat cell volume was directly proportional to lipolysis in obese subjects, both before and after weight reduction, and in control subjects. Insulin-induced antilipolysis and lipogenesis were completely normalised after weight reduction.

CONCLUSIONS/INTERPRETATION

Body-weight-reduced obese women had low basal and catecholamine-stimulated adipocyte lipolysis, presumably due to adipose tissue hyperplasia. This could make an important contribution to body weight gain following weight loss. Adipocyte insulin resistance is secondary to obesity.

Regulation of lipolysis and lipoprotein lipase after weight loss in obese, postmenopausal women

OBJECTIVE

To test the hypothesis that the greater beta-adrenoceptor (beta-AR)-stimulated lipolysis and sensitivity (half-maximal lipolytic response) in abdominal (ABD) adipocytes, greater gluteal (GLT) adipose tissue-lipoprotein lipase (AT-LPL) activity, and dyslipidemia associated with obesity in older women are modifiable by weight loss (WL) and are not due to menopause or aging.

RESEARCH METHODS AND PROCEDURES

The metabolic effects of 6 months of hypocaloric diet and low-intensity walking WL program on the regional regulation of in vitro lipolysis and AT-LPL activity in subcutaneous ABD and GLT adipocytes were measured in 34 obese (48.7 +/- 0.7% body fat, mean +/- SE) postmenopausal (59 +/- 1 years) white women.

RESULTS

The lipolytic responsiveness to the beta-AR agonist isoproterenol and basal lipolysis in the presence of 1 U/mL adenosine deaminase-uninhibited (lipolysis) were greater (p < 0.01) in ABD than GLT adipocytes before and after WL, but there were no regional differences in postreceptor (dibutyryl 3',5'-cyclic adenosine monophosphate)-stimulated lipolysis. beta-AR sensitivity was greater in ABD than GLT adipocytes before (p < 0.01) but not after WL. Regional AT-LPL did not change after WL, but the change in the activity of ABD (but not GLT) AT-LPL correlated with the baseline adenosine deaminase-uninhibited lipolysis (r = 0.38, p = 0.03). There were no relationships between the declines in plasma triglyceride or increases in high-density lipoprotein cholesterol associated with WL and the changes in regional fat cell metabolism.

DISCUSSION

Thus, despite improving lipoprotein lipid profiles in obese, postmenopausal women, WL does not affect the regulation of regional fat metabolism, and a greater tonic inhibition of basal lipolysis by endogenous adenosine may increase the activity of AT-LPL after WL and predispose older women to develop ABD adiposity.

Exercise-induced weight loss preferentially reduces abdominal fat

PURPOSE

To investigate whether abdominal fat is reduced in response to substantial weight loss induced by exercise in young obese men.

METHODS

Thirty obese men (mean age 19.8 +/- 0.6 yr) were evaluated before (pretraining) and after (posttraining) 4 months of regimented training in the Singapore Armed Forces. There were 30 obese male subjects (mean age 19.2 +/- 1.3 yr) without training who were monitored as control subjects. Fat free mass (FFM), fat mass, and percent body fat were determined from skinfold measurements. Differences between pre- and posttraining responses were analyzed with a paired -test.

RESULTS

Subjects lost 12.0 +/- 3.6 kg (P < 0.001) from pre- to posttraining, which was attributable to a reduction in fat mass (P < 0.001), as FFM was unchanged. Both waist circumference (WC) and hip circumference (HC) decreased (P < 0.01), the reduction in WC (13.7%) being greater than the reduction in HC (7.7%) as reflected by the decrease in waist-to-hip ratio (WHR; P < 0.001). These data reveal that large exercise-induced weight losses are associated with maintenance of FFM. The significant reduction in WHR indicates a greater mobilization of abdominal fat and a preferential loss of fat from this region.

CONCLUSIONS

Large exercise-induced weight loss is associated with a preferential reduction in abdominal fat and a corresponding maintenance of FFM. Such an effect on body composition should reduce disease risk and the eventual weight regain that typically follows diet-induced weight losses with obese subjects.

Weight loss and plasma lipids

Although weight loss is associated with improvements in the plasma lipid profile, factors other than weight loss per se are involved. Energy restriction resulting in even modest weight loss suppresses endogenous cholesterol synthesis, which contributes to observed decline in circulating lipid concentrations. Whether individuals have stabilized weight or are still actively losing weight affects the magnitude of LDL cholesterol reduction as well as the direction of HDL cholesterol change. Hence, it is important to consider the timing of lipid measurements in the interpretation of the plasma lipid response to weight loss. Another important factor is the dietary composition of the weight loss strategy, with evidence that dietary fatty acid profile and amount can differentially influence the lipid response similar to that observed in energy balance studies. Other issues such as gender, and exercise during weight loss are also relevant. However, whether the lipid changes that are observed in the short term are sustained in the long term and whether the manner of weight loss has any impact on long-term outcomes remains to be determined.

Bioelectric impedance and hydrostatic weighing with and without head submersion in persons who are morbidly obese

OBJECTIVE

To compare hydrostatic weighing with and without head submersion and bioelectric impedance analysis (BIA) for measurement of body composition of persons who are morbidly obese.

DESIGN

Body composition was determined using 3 methods: hydrostatic weighing with and without head submersion and BIA. Residual volume for the hydrostatic weighing calculation was determined by body plethysmography.

SUBJECTS

Subjects were 16 morbidly obese men (142.5 kg mean body weight) and 30 morbidly obese women (125.9 kg mean body weight) living in the Salt Lake County, Utah, area. Morbid obesity was defined as 40 kg or more over ideal weight.

STATISTICAL ANALYSIS

One-way, repeated-measures analysis of variance was followed by Scheffé post hoc tests; body-fat measurement method served as the repeated variable and percentage of body fat as the dependent variable. Men and women were analyzed separately. In addition, degree of agreement between the 3 methods of determining body composition was determined. A regression equation was used to calculate body density for hydrostatic weighing without head submersion. Two new BIA regression equations were developed from the data of the 16 men and 30 women.

RESULTS

Values for percentage body fat from hydrostatic weighing with and without head submersion (41.8% vs 41.7%, respectively) were the same for men but differed for women (52.2% vs 49.4%, respectively, P < .0001). Values for body fat percentage measured by BIA were significantly lower for men (36.1%) and women (43.1%) (for both, P < .0001) compared with values from hydrostatic weighing methods. BIA underpredicted percentage body fat by a mean of 5.7% in men and 9.1% in women compared with the traditional hydrostatic weighing method.

APPLICATIONS/CONCLUSIONS

BIA tended to underpredict the measurement of percentage body fat in male and female subjects who were morbidly obese. Hydrostatic weighing without head submersion provides an accurate, acceptable, and convenient alternative method for body composition assessment of the morbidly obese population in comparison with the traditional hydrostatic weighing method. In population screening or other settings where underwater weighing is impractical, population-specific BIA regression equations should be used because general BIA equations lead to consistent underprediction of percentage body fat compared with hydrostatic weighing.

Beneficial effect on serum apo AI, apo B and Lp AI levels of Ramadan fasting

In order to investigate for the first time in Morocco the effect of fasting in Ramadan, the ninth lunar month of the muslim year, on lipoprotein metabolism, we determined the levels of serum apolipoproteins; apolipoprotein AI (apo AI), apo B, apo AIV and those of lipoprotein particles; apo AI-containing lipoprotein particles (Lp AI) and also apo AI and apo AII containing lipoprotein particles (Lp AI:AII) in a group of 32 healthy, volunteer adult males. Determination of all these parameters was carried out on each week of the month of Ramadan and the results are compared with the pre-fasting and the post-fasting values. Ramadan fasting reduces significantly serum apo B (P < 0.05), while serum apo AI is significantly increased (P < 0.05) compared with the pre-fasting period. The increase of apo AI occurred on day 29 of Ramadan by 11.8%. Serum apo AIV was unchanged during the fasting period indicating that food intake during Ramadan is not based on lipid diet. The observed diet pattern during Ramadan showed an increase of total energy intake based on carbohydrates (+1.4% of total energy), proteins (+0.4% of total energy) but not on fat (-0.7% of total energy), compared with a usual diet used in the rest of the year. The fat diet is high in monounsaturated (P < 0.05) and polyunsaturated fatty acid in contrast to saturated fatty acid which decreased (P < 0.05) during Ramadan. On the other hand, analysis of serum Lp AI and Lp AI:AII showed that the levels of Lp AI:AII were unchanged but those of Lp AI were significantly increased (P < 0.01) at the end of Ramadan. These findings show that feeding behaviour that occurs during Ramadan beneficially affects serum apolipoprotein metabolism and may contribute to prevention of cardiovascular diseases.

Waist circumference as a measure for indicating need for weight management

OBJECTIVE

To test the hypothesis that a single measurement, waist circumference, might be used to identify people at health risk both from being overweight and from having a central fat distribution.

DESIGN

A community derived random sample of men and women and a second, validation sample.

SETTING

North Glasgow.

SUBJECT

904 men and 1014 women (first sample); 86 men and 202 women (validation sample).

MAIN OUTCOME MEASURES

Waist circumference, body mass index, waist:hip ratio.

RESULTS

Waist circumference > or = 94 cm for men and > or = 80 cm for women identified subjects with high body mass index (> or = 25 kg/m2) and those with lower body mass index but high waist:hip ratio (> or = 0.95 for men, > or = 0.80 women) with a sensitivity of > 96% and specificity > 97.5%. Waist circumference > or = 102 cm for men or > or = 88 cm for women identified subjects with body mass index > or = 30 and those with lower body mass index but high waist:hip ratio with a sensitivity of > 96% and specificity > 98%, with only about 2% of the sample being misclassified.

CONCLUSIONS

Waist circumference could be used in health promotion programmes to identify individuals who should seek and be offered weight management. Men with waist circumference > or = 94 cm and women with waist circumference > or = 80 cm should gain no further weight; men with waist circumference > or = 102 cm and women with waist circumference > or = 88 cm should reduce their weight.